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Ligamentous Restraints to External Rotation of the Humerus in the Late-Cocking Phase of Throwing

Ligamentous Restraints to External Rotation of the Humerus in the Late-Cocking Phase of Throwing

Authors :
Michael J. Bey
John E. Kuhn
Louis J. Soslowsky
Ralph B. Blasier
Laura J. Huston
Source :
The American Journal of Sports Medicine. 28:200-205
Publication Year :
2000
Publisher :
SAGE Publications, 2000.

Abstract

The late-cocking phase of throwing is characterized by extreme external rotation of the abducted arm; repeated stress in this position is a potential source of glenohumeral joint laxity. To determine the ligamentous restraints for external rotation in this position, 20 cadaver shoulders (mean age, 65 +/- 16 years) were dissected, leaving the rotator cuff tendons, coracoacromial ligament, glenohumeral capsule and ligaments, and coracohumeral ligament intact. The combined superior and middle glenohumeral ligaments, anterior band of the inferior glenohumeral ligament, and the entire inferior glenohumeral ligament were marked with sutures during arthroscopy. Specimens were mounted in a testing apparatus to simulate the late-cocking position. Forces of 22 N were applied to each of the rotator cuff tendons. An external rotation torque (0.06 N x m/sec to a peak of 3.4 N x m) was applied to the humerus of each specimen with the capsule intact and again after a single randomly chosen ligament was cut (N = 5 in each group). Cutting the entire inferior glenohumeral ligament resulted in the greatest increase in external rotation (10.2 degrees +/- 4.9 degrees). This was not significantly different from sectioning the coracohumeral ligament (8.6 degrees +/- 7.3 degrees). The anterior band of the inferior glenohumeral ligament (2.7 degrees +/- 1.5 degrees) and the superior and middle glenohumeral ligaments (0.7 degrees +/- 0.3 degrees) were significantly less important in limiting external rotation.

Details

ISSN :
15523365 and 03635465
Volume :
28
Database :
OpenAIRE
Journal :
The American Journal of Sports Medicine
Accession number :
edsair.doi.dedup.....10fd166f1ba32a4146b0fd6a7eb5607a
Full Text :
https://doi.org/10.1177/03635465000280021001